AWS r5.xlarge vs i3.xlarge

I am wondering what instance type is best for a small cassandra cluster on AWS.

Actually I'd like to compare, or have your opinion about the following instances:

r5d.xlarge (4vCPU, 19ecu, 32GB ram and 1 NVMe instance store 150GB)

Need to attach a 600/900GB ESB

i3.xlarge (4vCPU, 13ecu, 30.5GB ram and 9.5TB NVMe instance store)

Both have up to 10Gb networking.

I see AWS mark i3 as the NoSQL DB instances nevertheless r5d seems bit better CPU wise. Putting a decently sized gp2 EBS I should have enough IOPS especially we think to put commitlog and such on the 150GB NVMe storage.